Antiperspirant salts are composed of cationic metal oxide part of aluminum and aluminum-zirconium and an anionic part of a halide such as Cl.sup.- and less commonly Br.sup.- or I.sup.-. Nitrate salts are also known in the art. These antiperspirant salts, due to their cationic/anionic characteristics, are soluble in water.
Typical aluminum halohydrate salts are believed to be composed of five cationic components. Evidence also exists that aluminum-zirconium-glycine salts are composed of two zirconium species, heteronuclear aluminum-zirconium oligomeric components as well as the five aluminum halohydrate species. In either the aluminum or the aluminum-zirconium salts, a high degree of hydrogen-bonding exists, especially at high solid concentrations. The halohydrate salts, when in highly concentrated solutions, are large agglomerates of charged polyoxides, and their positive charge is counter balanced by the negatively charged halide or nitrate ions.
In recent years a lot of interest has been expressed in decreasing the hydrophilic character of the salts, and creating materials that are more compatible with the hydrophobic nature of their delivery system. One way of introducing hydrophobic properties into the salts, which is encompassed by this invention, is to modify the cationic surface of the salt by attaching an anionic lipophilic component chain to the salt. Carboxylate, sulfate and phosphate compounds are useful as the anionic lipophilic component.
The use of carboxylic acids in antiperspirant formulations is known in the art. For example U.S. Pat. No. 4,174,386 to Spitzer et al. teaches a highly concentrated aerosol antiperspirant composition which contains 0.1 to 5 weight percent of a solid saturated aliphatic carboxylic acid having 14 to 22 carbon atoms in a straight chain. The solid saturated aliphatic carboxylic acid is blended into the formulation and is not used to directly alter the antiperspirant salt nor is it taught to react with the antiperspirant salt in any manner. The use of the solid saturated aliphatic carboxylic acid improves the adherence of the antiperspirant salt to the skin.
Modification of antiperspirant or aluminum salts using organic materials to obtain certain properties is also known in the art. GB Patent No. 1536222 to Shelton teaches an anhydrous antiperspirant composition which contains 10 to 30 weight percent of an alcohol-soluble antiperspirant salt complex. The alcohol-soluble antiperspirant salt complex is produced by reacting an astringent antiperspirant salt with a polyhydric alcohol. These salt complexes may be formulated into mechanically sprayable (not aerosol) antiperspirant compositions. Additionally, EP Patent No. 326155 to Fukasawa teaches a novel polyaluminum dialkylphosphate that is useful as an oil gelling agent. The polyaluminum dialkylphosphates are produced by reacting a dialkyl phosphate with a polyaluminum salt. The compositions taught by Fukasawa are not shown to have any use in antiperspirants or to have any antiperspirant activity.
Further, Australian Patent No. 22750 to Schang et al. teaches novel aluminum-magnesium salts that are produced through the reaction between an aluminum-magnesium-hydroxy sulfate clay and a salt of a carboxylic acids, such as sodium caprylate. The aluminum-magnesium clays are insoluble in water and the reaction is carried out as a suspension of the two solid reagents in water. Aluminum and aluminum-zirconium halohydrate salts which are used in the instant invention are very different in structure and chemistry from the Al/Mg synthetic clays used in the Australian 22750 patent.
It is an object of this invention to show novel aluminum and aluminum-zirconium salts that contain anionic lipophilic groups.
It is further an object of this invention to show a method for producing the novel aluminum and aluminum-zirconium salts.
It is further an object of this invention to show the use of the novel aluminum and aluminum-zirconium salts in antiperspirant compositions.
It is further an object of this invention to show the use of the novel aluminum and aluminum-zirconium salts as suspending agents.
It is further an object of this invention to show the use of the novel aluminum and alunimum-zirconium salts as rheological additives.
It is further an object of this invention to show a method for producing emulsions which in which the novel aluminum and aluminum-zirconium salts function as the surfactants.